A scalable recirculating shuffle network with deflection routing

Abstract

We describe a high-speed optical wide area network (WAN) architecture called the multi-cylinder ShuffleNet (MCSN). Its basic topology is a recirculating shuffle exchange network with an all-optical data path from source to destination. The network capacity and performance is improved by augmenting it with multiple parallel copies of the original topology called routing cylinders. This approach avoids the use of a global request/acknowledge mechanism by matching the rate at which packets can be input into the network to the rate at which packets can be transmitted through the network (without congestion). Packets are dynamically stored within the switching nodes (using only fixed delay line elements) and the links of the network, and congestion control within the network is handled by routing blocked packets onto alternative routing cylinders. The architecture is easily scalable, designed for bit-synchronous, packet asynchronous traffic and utilizes a simple distributed control scheme. Simulation results which demonstrate these features are given. IntroductionOptical interconnection networks offer the potential for bandwidth in the tens to hundreds of gigabitslsec over a given data path. Their primary limitation is that complex logic, data buffering and routing is difficult to perform in the optical domain. Our goal is to perform these functions as fast as possible while maintaining the data in all-optical form as much as possible to avoid electronicloptical conversions.Current optical communication networks fall into several categories: i) ring or bus topologies with optical interconnects [l]-[S]; ii) circuitlpacket switched networks for packet asynchronous traffic [9]-[ 111; iii) circuit switched networks using global electronic control with optical data paths in the switching nodes and links [12], 1131; and iv) packet switched optical routing networks for packet synchronous traffic [14]-[24]. Ring or bus topologies are simple to implement and maintain data in optical form while in the network but have only one data path for all communications. Circuitlpacket switched networks with optical point-to-point links and electronic paths within the switching nodes [9], [ 101 provide multiple communication paths 0-8186-7591-8196 $5.00 0 1996 IEEE Proceedings of MPPOI '96and allow for packet asynchronous traffic, but the link data rate on each path is limited by optoelectronic conversions. Additionally, circuit switched networks are limited by the requestlacknowledge cycle time for path establishment. The packet switched network described in [ 111 routes packet asynchronous traffic with optical switching nodes but requires monitoring the status of a switching node before sending a new packet into the network. Synchronously switched optical schemes provide multiple data paths with the enhanced throughput of optics, but these networks are not suitable for distributed networks where packet synchronization is not possible without the use of variable delay electronic buffers. Current optical network implementations do not off...